STUDIES ON DEALUMINIZATION PROCESS OF FAUJASITE BY MONTE-CARLO METHOD
用Monte-Carlo方法研究八面沸石的脱铝过程

In principle, four rypes of aluminum ions on the faujasite framework may be distinguished according to the next neighbour number (0,1,2,3) of aluminum appearing around their environment. The hydrogen ions associated with type-O aluminum ions are to be identified as "strong" acid, and those associated with types 1,2 and 3, as "weak" acid. In a dealuminization process, the "weak acid" aluminum ions (types 1,2 and 3) are removed preferably over the "strong acid" type-O. Based on first-order kinetics, the concentrations of all the four types aluminum ions upon dealuminization can be described in terms of the Monte-Carlo simulation of the dealuminization process of the faujasite. We conclude that the concentration of the strong acid center in dealuminization faujasites come up to its maximum around Si/Al 6.68. We also conclude that the more difference between dissolving rate constants for "strong" and "weak" aluminum ions the denser strong acid in dealuminization faujasite could be expected.